The subject matter disclosed herein generally relates to pitot tubes. More specifically, the present disclosure relates to ice prevention and removal from pitot tubes.
A pitot tube is widely used to determine airspeed of an aircraft or other vehicle, or to measure air or gas velocities in industrial applications. In particular, by measuring stagnation pressure of a fluid driven into the pitot tube, together with a measured static pressure, the airspeed of the aircraft can be determined. In certain flight conditions, the pitot tube may be subject to ice accumulation from moisture in the air. For this reason, pitot tubes are equipped with heating elements to prevent such ice accumulation. Further, in other conditions, the pitot tube may ingest ice crystals which then accumulate inside of the pitot tube and cause failure in its operation. A typical pitot tube is substantially cylindrical with an internal diameter containing the heating elements, or coils. Forward of the heating elements is a tip portion that extends radially from a throat diameter, typically smaller than the internal diameter, to an outer diameter of the pitot tube. The tip portion extends axially from the throat to a pitot tube inlet. The pitot tube inlet has a diameter greater than the throat. An exterior of the typical tube is cylindrical along its length to the inlet. Such a tube has a large surface area of material in the tip portion forward of the heater, and is difficult to heat and therefore to prevent ice accumulation thereon. Further, a large inlet diameter allows for proportionally more ice crystals to be ingested by the pitot tube. Such ingested ice crystals must be melted by the heating elements and drained from the pitot tube.